In general, applications executing on a host may communicate with one or more peers via a network using various communication protocols. For example, the International Standards Organization (ISO) has defined a framework for such protocols, known as the “7 layer model.” Some host operating systems have the capability to manage the network traffic generated by the host. Traffic management includes, for example, quality of service based scheduling, rate control, flow control and congestion control.
Traffic management for high speed network adapters uses a lot of processing resources, which may consume a large fraction of the processing resources available in a system, or even exceed its capabilities. Another issue to be dealt with by an operating system of a host, when interfacing to a high speed network adapter, is the scheduling of packet transmissions to and from the adapter.
It is known to offload at least some specific protocol processing functions to intelligent network interface circuitry. For example, checksum offload is a common feature implemented in a modern network adapter. Example checksums supported in the context of the Internet include Internet Protocol (IP), Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) checksums.